This application claims the benefit of a Japanese Patent Application No. 2001-163252 filed May 30, 2001, in the Japanese Patent Office, the disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to write and/or erase methods and storage apparatuses, and more particularly to a write and/or erase method (hereinafter simply referred to as a write/erase method) which sets parameters which are used when writing and/or erasing (writing/erasing) with respect to a recording medium depending on a write and/or erase power (write/erase power), and to a storage medium which employs such a write/erase method.
In addition to magneto-optical disk units which record and/or reproduce (record/reproduce) information with respect to a land of a magneto-optical disk, there are proposed magneto-optical disk units which record/reproduce the information with respect to both a land and a groove of the magneto-optical disk. By employing the so-called land-groove recording system which records the information on both the land and the groove of the magneto-optical disk, it is possible to increase the recording density on the magneto-optical disk.
2. Description of the Related Art
In an optical recording medium, typified by a magneto-optical disk, which employs the land-groove recording system and has a narrow track pitch, there is a possibility of deteriorating a signal reproducing performance of a target track due to a signal interference caused by a signal written on an adjacent track. It is known that this signal interference is dependent on a write power of a light beam which is used to write the signal on the adjacent track, and dependent on a positional error of the light beam with respect to the track. In addition, it is also known that a tolerable amount of the positional error of the light beam with respect to the track decreases when the write power becomes large, and that the tolerable amount of the positional error of the light beam with respect to the track increases when the write power becomes small.
In other words, because the optical recording medium has the narrow track pitch, a thermal conduction easily occurs with respect to the adjacent track which is adjacent to the target track on which the information is written if the write power is large. As a result, the signal written on the adjacent track may be erased or, the signal written on the target track may leak into the adjacent track. For this reason, the write signal level of the adjacent track is deteriorated when the write power is large. Hence, a method of suppressing deterioration of the write signal level of the adjacent track by adjusting the write power has been proposed in a Japanese Laid-Open Patent Application No. 11-16251, for example.
Furthermore, when the write power is large, the signal from the adjacent tracks leaks when reading from the target track, because the optical recording medium has the narrow track pitch. Especially when the write power of the adjacent track is large, the signal read from the adjacent track easily leaks into the signal read from the target track.
According to the conventional storage apparatus, however, a limit of the write power is obtained on the assumption that the light beam scans the center of the track on the recording medium. For this reason, when an external vibration or shock is applied on the storage apparatus, the light beam actually scans a position deviated from the center of the track, and there was a possibility of deteriorating the signal of the adjacent track as described above.
On the other hand, a Japanese Laid-Open Patent Application No. 2000-182292 proposes a method which varies the write power during a write retry process, obtains a statistical write success rate with respect to the write power, and controls the write power to an optimum value based on the write success rate. In this case, the write power and/or the erase power are set intentionally, but it is necessary to set an off-track detection slice level which is used for detecting an off-track of the light beam by assuming a case where the write power and/or the erase power are high. As a result, the off-track is monitored very severely, and there was a possibility of detecting the off-track too sensitively.